trying to trace my roots

Hello this is such a complicated family tree as my family is so big so i will start with my mothers side. My granda is McGilligan From Ballerin (Co Derry) he lived in Australia for years and now have cousins over there.he is part of a family of 13, 2 who are dead, Brain McGilligan who died in Australia while working on the railroads and Tom who died in September in Ringsend, Coleraine. My granny was lynch before she married who come from Greencastle in co Donegal.My great granda lived until he was 96 he died in 2000, in Ringsend. My Fathers side are all from Dungiven, Derry. My granda is McGilligan from Dungiven, and all i know is my granny was mc closkey from a place called the benedy which is outside dungvien. so any information would be helpful! thanks